Double-acting equalizing-cylinder for fluid-pressure systems.



, PATBNTED 001*:1af1904. G. M. SPENCER & 0. J. GRELLNER. I DOUBLE ACTING EQUALIZING CYLINDER FOR FLUID PRESSURE sYsTEMs. APPLICATION FILED 0015 1903.

no MODEL.

(gm/ 22001 and) a fff'e liwr Illlll Patented October 18, 1904.

- UNIT D"STATES PATENT OFFI E,"

GEORGE M. SPENOER AND CHRISTOPHER J. GRELLNER, OE T. LOUIS,

. MISSOURI. I I

DOUBLE-ACTING EQUALIZING-CYLIND ER FOR FLUID-PRESSURE SYSTEMS.

SPECIFICATION forming part of Letters Patent No. 772,842, dated October 18, 1904.

Application filed October 5,1903.

T CLZZ whom it may concern.-

Be it known that we, GEORGE M. SPENCER and CHRISTOPHER J. -GRELL'N'ER,-citizens of the United States, residing in the city of St. Louis, in the State of Missouri, have invented certain new and useful Improvements in Double Acting Equalizing Cylinders for Fluid-Pressure Systems, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification.

Our invention relates to a cylinder for fluidpressure apparatus in which double action is furnished and in which the fluid-pressure against the piston therein is rendered equal or approximately equal at both sides of said piston in order that when the piston has been actuated in one direction the pressure medium against both of its faces to equalize it.

cylinder is of particular utility inconnection may be equalized in the cylinder at both sides of the piston and will have thesame effect The i with that class of fluid-pressure brake systems set forth in our application for Letters Patent of the United States,filed June 25, 1903, Serial NO. 162,997. 7

Our invention consists in features of novelty hereinafter fully described, and pointed out'in the claims.

' Figure I is a longitudinal section of our double-acting equalizing-cylinder. Fig. I1 is v a cross-Section taken on line'II II, Fig. I.

pressure medium to deliver such medium into the cylinder, and the pipe 8 leads frornthe cylinder to a point of discharge to conduct the pressure medium from said cylinder, and

Serial no. 175,7 9. (No model.)

'both of said pipes are brought into coinciding relation with each other, so that they may have communication similar to that described in our application hereinbefore referred to with reference to the equalizing-pipes connected to the cylinder therein.

9 designates a piston that operatesin the" cylinder 1 and to one side Of which is connected a tubular stem 10, which operates through the cylinder-head 2 and is encircled by suitable pistOn-rod packing 11.

12 is a piston-rod extending through the tubular system 10 and having bearing at its inner end against the piston 9. This pistonrod is separated from the tubular stem sufiiciently to furnish a space between said members that has communication with a duct 13 in the piston 9. The piston-rod-12 receives the connection of a brake-lever, as seen at 14,

'Fig. I, or anyother member to which it may be desired to communicate motion. 15 designates a second tubular stem Secured to the piston 9 at its Opposite side from that to which the stem 10 is'secured. This stem 15 extends through the cylinder-head 4E and a suitable packing 16 and operates'in the tubular extensions 5, carried by said cylinderhead..

17 designates a spring surrounding the tubular stem 10 and positioned between the piston 9 and the cylinder-head 2, its outer end being preferably located in the pocket extension of said cylinder-head, as seen in Fig. I.

' This spring is designed forservice in returning the piston 9 to the highpressure-receiving end of the cylinder 1, to which the pres-- sure medium of pipe 7 leads, the spring be ing brought into service after the piston 9 has completed its forward stroke and the pressure medium in the cylinder at both sides of the piston has been equalized. In the practical use of Our cylinder pressure medium, such as air under heavy'pressure, is conducted to the cylinder through the pipe 7 and on entering the cylinder at the rear side of the piston therein acts against the piston to effect its forward stroke and carry the piston-rod 12 in a corresponding direction to actuate the brake-lever or other mem her connected thereto. During the forward stroke of the piston the spring 17 is compressed and at the same time the tubular stem 15 is carried forwardly with the piston and by its presence in the cylinder-space compensates for the diiference in displacement of pressure medium at opposite sides of the piston that would be present in the instance of the employment of the piston-rod 12 alone or said piston-rod and the tubular stem 10 surrounding it. It will therefore be seen that equal pressure surfaces at both sides of the piston are furnished and that therefore pressure medium at either of its sides may act thereagainst with uniform driving power, owing to the equal area of piston-surfaces afforded to the pressure medium. After the piston has made its forward stroke, as stated, the pressure medium in the cylinder is equalized at opposite sides of the piston by furnishing communication from the pipe 7 to the pipe 8 in any suitable manner, such as that described in our application for patent hereinbefore referred to, and when such communication is established the pressure at the rear of the piston will be in part transferred to the forward side of thepiston and the pressure thus equalized at the two ends of the cylinder. As soon as this equalization has been secured the spring 17 comes into action and effects return stroke of the piston 9. This it is permitted to do by reason of the presence of the tubular stem 15, located at the rear side of the piston, which offsets the displacement in the cylinder at the rear side of the piston to a degree corresponding to the displacement incurred by the presence of the piston-rod at the forward side of the piston.

The space furnished between the piston-rod 12 and tubular sleeve 10 and the duct 13 in the piston 9 are provided for the purpose of furnishing communication between the cavity 6 in the tubular extension 5, in which the stem 15 operates, and the exterior of the cylinder in order that there may be constant circulalation of air into and from said cavity to prevent the formation of air-cushion or vacuum therein.

While we have described in connection with our construction of double-acting and equalizing cylinder the stems 10 and 15 as furnisl ing means through which the displacement at opposite sides of the piston in the cylinder is rendered equal and the spring 17 for causing return stroke of the piston, we do not wish to be limited to the precise arrangement set forth nor to the use of the spring for causing return stroke of the piston. In this connection we would mention that instead of making use of the spring the displacement member at the side of the piston at which said spring is located may be of a less size than the displacement member at the opposite side of the piston and the spring dispensed with, in which case there would be a greater pressure-receiving area at the forward side of the piston for the pressure medium to act against when equalizing in the cylinder, and therefore the same action against the piston be furnished as where the spring is used. It is also evident that the piston in the cylinder may be actuated to exert a pull upon the piston-rod instead of pushing it, and in such instance the displacement member at the rear side of the piston may be of less diameter than the displacement member at the forward side to gain the same action as that just previously referred to.

While we have described the displacement member 15 as a tubular stem, it is obvious that displacement members of other forms may be usedsuch, for instance, as a flexible member, in the use of which a vent to avoid a cushion or vacuum in the part in which the displacement member operates may be dispensed with.

While we have described the vent from the tubular extension in which the displacementstem 15 operates as furnished from said stem through the duct 13 and through the tubular piston-rod-inclosing stem 10, it is obvious that this vent may be furnished in any other suitable manner, such as by placing a duct in the tubular extension 5.

e claim as our invention 1. A fluid-pressure cylinder having means therein for approximately equalizing the action of pressure medium at both faces of the cylinder-piston, and means exterior of said cylinder for admitting pressure medium into each end of the cylinder, substantially as set forth.

2. The combination with a fluid-pressure cylinder proper and piston therein, of means in said cylinder for rendering the displacement of pressure medium approximately equal at both sides of said piston, and means exterior of said cylinder for admitting pressure medium into each end of the cylinder, substantially as set forth.

3. The combination with a fluid-pressure cylinder proper and piston therein, of members carried by said piston by which the displacement of pressure medium at both sides of said piston is rendered approximately equal, and means exterior of said cylinder for admitting pressure medium into each end of the cylinder, substantially as set forth.

4. The combination with a fluid-pressure cylinder proper and piston therein, of members carried by said piston by which the displacement of pressure medium at both sides of said piston is rendered equal or approximately equal; and means exterior of said cylinder for admitting pressure medium into each end of the cylinder, said cylinder being provided with a vent communicating with the exterior air to avoid the presence of cushion or a vacuum in a part in which a displacement member operates, substantially as set forth.

5. The combination with a fluid-pressure cylinder proper and piston therein, of a piston-rod at one side of said piston to be opercylinder proper and piston therein, of a piston-rod at one side of said piston to be operated thereby, a tubular stern carried by said piston at the side opposite to that at which said piston-rod is located, and'means exterior of said cylinder for admitting pressure medium into each end of the cylinder, substantially as set forth.

' 7. The combination with a fluid-pressure cylinder proper and piston therein, of means for equalizing the pressure-medium-contacting space against said piston, a spring acting against said piston at one side thereof, and means exterior of said cylinder for admitting pressure'mediuminto each end of the 'cylinder, substantially asset forth.

8. The combination with a fluid-pressure cylinder proper and piston therein,.of a pis-.

ton-rod at one sideof said piston, a tubular stem surrounding said piston-rod and connected to said piston, and a tubular stem connected to said piston at the opposite side to that at whichsaidpiston-rod and first-named tubular stem are located, substantially as set forth.

9. The combination with a fluid-pressure cylinder proper and piston-therein, of a tubular extension projecting from one of the heads of said cylinder, a tubular stem connected to said piston and operating in said tubular ex,

tension, and a piston-rod located'at the opposite side of said piston to that at which said tubular stem is located, substantially as set forth.

V 10. The combination with a fluid-pressure cylinder proper and piston therein provided with a duct, of a tubular extension projecting from one of the heads of said cylinder, a tubular stem connected to said piston and oper ating in said tubular extension, a piston-rod located at the opposite side of said piston from that at which said tubular stem is located, and

a tubular stem surrounding said piston-rod and connected to said piston, substantially as set forth.

11. The combination with a fluid-pressurecylinder proper and piston therein, of an extension projecting from one of the heads of said cylinder, a stem connected to said piston and operating in said extension, a piston-rod located at the opposite side of said piston from that at which said stem is located, a tubular stem surrounding said piston-rod and connected to said piston, and a spring surrounding said piston-rod and tubular stem and bearing against said piston, substantially as set forth.

In testimony whereof we have hereunto set our hands this 25th day of September, 1903.

GEO. M. SPENCER. CHRISTOPHER J. GRELLNER. In presence of E. S. KNIGHT, BLANOI-IE HOGAN; 

